Ask, task, task, cask, flask, mask, hask.†

ASM.

Chasm, spasm, miasm, enthusiasm, cataplasm, phantasm.

ASP.

Asp, clasp, rasp, gasp, grasp, hasp, wasp (?).

ASQUE.

Casque, mask, etc.

ASS.

Ass, brass, class, grass, lass, mass, pass, alas, amass, cuirass, repass, surpass, morass, etc.

AST.